The present invention relates to a method for the reconstruction of the anterior cruciate ligament of a patient. More particularly it relates to such a method in which a tendon graft is used to replace the ruptured anterior cruciate ligament.
As is well known the human knee comprises an articulation of the femur, the tibia and the patella. The femur and the tibia are maintained in a condition of stable articulation by a number of ligaments of which the principal ones are the anterior and posterior cruciate ligaments and the lateral ligaments. The rupture of the anterior cruciate ligament is relatively commonly encountered as a result of sporting injury or the like. This rupture leads to knee instability and can be a debilitating injury.
There have been a number of procedures designed to reconstruct the anterior cruciate ligament. Initially, attempts were made to replace the anterior cruciate ligament with tendons harvested from elsewhere in the body. These tendons were connected respectively to the femur and the tibia by staples, screws or the like inserted exteriorly into the bone and forming an external attachment to which the tendon could be connected externally of the bone. In some cases, the tendon passed over the top of one of the femoral condyles before attachment to the femur and in other cases a hole was drilled through the femur from outside the bone into the intercondylar notch. These attempts at anterior cruciate ligament reconstruction had mixed success. The tendon tended to break at its point of connection to the bone, or become loose over time, indicating that the tendon-bone interface was crucial for effective anterior cruciate ligament reconstruction.
These problems led to the use of bone-tendon-bone grafts generally harvested from mid-third patella tendon with a bone block at each end. Each bone block is inserted into an appropriate hole drilled in the femur or the tibia and secured in place by a screw driven between the wall of the hole and the bone block. While this system has been very successful in many respects a significant number of patients continue to have patella-femoral problems, especially over the mid-third patella tendon donor site.
In an effort to overcome these problems it has been proposed to suture hamstring tendon to a bone block derived from coring the tibial tunnel and to thereby manufacture a bone/tendon/bone graft similar to a mid-third patella tendon graft. The present inventors have found that the bone quality is extremely variable. This results in poor fixation and poor intra-operative pull-out strength in some cases. This procedure was also found to be a very demanding surgical procedure, and therefore difficult to reproduce.
The present invention consists in a method for the reconstruction of the anterior cruciate ligament of a patient comprising the steps of:
a) forming a tendon graft from tendon, other soft tissue or artificial tendon;
b) forming a hole through the patient""s femur from a suitable point in the intercondylar notch therein anteriorly and laterally, the cross-sectional area of at least an end portion of the hole through the femur adjacent the intercondylar notch being sufficient to receive an end of the tendon graft and a suitable screw, peg or other fixation device having a leading end and a trailing end;
c) forming a suitably positioned hole through the patient""s tibia opening at one end adjacent the cross-sectional medial tibial spine of the tibia of an area sufficient to receive the other end of the tendon graft;
d) drawing one end of the tendon graft into the enlarged end portion of the hole in the femur and simultaneously or sequentially drawing the other end of the tendon graft into the hole in the tibia;
e) inserting the leading end of a fixation device into the hole in the femur from the intercondylar notch end thereof until the trailing end of the fixation device is at least adjacent that end of the hole, and the tendon graft is pressed directly and firmly against a sidewall of the hole in the femur by the fixation device; and
f) after tensioning the tendon graft appropriately, securing the other end of the tendon graft to the tibia.
It has been surprisingly found that, even without the presence of a bone block, a screw or other similar fixation device can adequately secure the tendon graft in place in both the femoral hole and the tibial hole. The initial pull out strength is high and with time permanent fixation is achieved through bone ingrowth into the tendon graft.
In a preferred embodiment of the invention the tendon graft comprises tendon or tendons derived from the hamstring tendons of the patient or from the achilles tendons of cadavers. Most preferably, the tendons are the semitendonosus and gracilis tendons of the patient harvested from the same leg as has the deficient anterior cruciate ligament. The invention could be practised using artificial tendon material or other bodily soft tissue such as ligament. Suitable synthetic plastics materials have been proposed for use in biological applications and could be used in place of natural tendon.
The tendon or tendons forming the tendon graft are preferably doubled over about their mid-point and trimmed to a desired length. The doubled over end and the free ends are preferably then each bound together over a length approximately equal to the length of the tendons that will extend through the holes in the femur and the tibia. Preferably, the ends of the tendon or tendons will be bound together using a Krakow suture or modified baseball stitch. A suture may also be connected to the tendon graft at each end. This suture may be used to draw the tendon graft through the respective holes and to tension the tendon graft prior to insertion of the fixation device in the tibial hole.
It is preferred that the hole in the femur is initially drilled as a guide hole of sufficient diameter to receive a suitable guide pin. The hole is then enlarged at least to a depth sufficient to receive an end portion of the tendon graft. This enlargement may be carried out using a cannulated drill guided on the guide pin. It is preferred, however, that the hole is enlarged using a rotary awl that enlarges the hole by compressing or compacting the bone around the original hole. It is particularly preferred that the size of the enlarged portion of the hole is sized to the size of the tendon graft to be placed in the hole. The cross-section area of the hole is desirably equal to or only very slightly greater than the cross-sectional area of the end portion of the tendon graft to be placed in the hole. If the fixation device has an enlarged head at its trailing ends it is desirable that the femoral hole, has adjacent the intercondylar notch a short section of further increased cross-sectional area to receive the head of the fixation device. Similarly it is preferred that the external end of the tibial hole has a short section of further increased cross-sectional area.
The tibial hole is preferably formed by drilling a hole having a cross-sectional area just sufficient to receive the other end portion of the tendon graft. As the tendon graft may vary in cross-sectional area along their length it is usual to position the larger end of the tendon or tendons in the tibial hole. A guide hole is preferably drilled from the outside and is guided so that at its exit from the tibia it will be at the coronal level of the median tibial eminence ⅔ of the way across the notch, lateral to medial, so as to remove the anterior cruciate ligament stump. The aim of positioning is so that the final hole causes the graft to arise from the centre of the notch coronally, sufficiently posterior to avoid impingement with the roof of the notch at full extension of the knee. The point of entry into the tibia is preferably selected such that the length of the hole is just sufficient to receive the other end portion of the tendon or tendons when the one end has been secured in the femoral hole. A guide pin is preferably placed through this guide hole and the hole enlarged to the desired cross-sectional area by a cannulated rotary awl guided along the guide pin.
In another aspect the present invention consists in a method for forming a hole in bone comprising the steps of
a) drilling a guide hole in the bone;
b) inserting a guide wire into the guide hole, and
c) passing a cannulated rotary awl down the guide wire while causing the awl to rotate to enlarge the guide hole to a desired size by compressing or compacting the bone around the guide hole.
The one end of the tendon graft is preferably drawn into the femoral hole by a suture that is connected to one end of the tendon or tendons and is positioned to extend through the tibial hole, through the knee joint, through the femoral hole and out of the patient""s thigh. As the suture is pulled so the tendon graft is drawn through the tibial hole into the femoral hole. Using this method when the one end of the tendon graft is firmly drawn into the enlarged portion of the femoral hole the other end of the tendon graft will be just drawn into the outside of the tibial hole.
The tendon graft is preferably fixed in the femoral hole by being directly and firmly pressed against the sidewall of the hole by a screw. The screw is most preferably formed with a thread devoid of an outermost cutting line so that neither the tendon or tendons nor the suture stitches around them will be cut by a sharp thread on the screw. The screw preferably also has a hemispherical head and is placed in the hole anteriorly of the tendon graft. This causes the tendon graft to firstly be spread as an arc around a posterior part of the circumferences of the screw and secondly causes the tendon graft to be curved smoothly around the head as it exits the femoral hole. Instead of a screw the tendon graft may be held in place in the femoral hole by a suitable pin, peg or other device that will force the tendon graft directly and firmly against the sidewall of the femoral hole. The head of the screw, pin, peg or the like should preferably be just below the surface of the femur. This ensures that the tendon graft is pressed against the sidewall of the femoral hole up to the condylar notch end of the hole. This prevents xe2x80x9cpistoningxe2x80x9d, i.e. movement under cyclic load of the tendon or tendon bundle longitudinally of the hole, of the tendon graft in the hole as happened with many prior art systems. This xe2x80x9cpistoningxe2x80x9d of the tendon or tendon bundle prevents bone ingrowth into the tendon graft and therefore hinders the permanent fixation of the tendon to the bone.
After the one end of the tendon graft is secured in the femoral hole a suture connected to the other end of the tendon graft is drawn tight and a suitable screw, pin, peg or the like is preferably inserted into the tibial hole from its outside end. The length of the screw, pin, peg or the like is preferably of such a length that, when its head is inserted until it is just below the outside surface of the tibia, it will extend substantially the full length of the tibial hole. The screw, pin or peg in the tibial hole the tibial hole serves to force the other end of the tendon graft into direct and firm contact with the side wall of the tibial hole. The tibial end of the tendon graft may, alternatively, be held in place by an exterior fixing such as a staple.